Plate-type heat pipe

ABSTRACT

A plate-type heat pipe includes a condensing plate, an evaporating plate and a first wick member. The evaporating plate cooperates with the condensing plate to define a hermetic container. Working fluid is contained in the container. The first wick member is formed on an inner surface of the condensing plate. The first wick member defines a plurality of through holes therein.

BACKGROUND

1. Technical Field

The present disclosure relates to heat pipes and, more particularly, to a plate-type heat pipe having good heat dissipation efficiency and stable and reliable performance.

2. Description of Related Art

Generally, plate-type heat pipes efficiently dissipate heat from heat-generating components such as a central processing unit (CPU) of a computer. A conventional plate-type heat pipe comprises a top plate and a bottom cover hermetically contacting the top plate to form a container. A continuous wick structure is adhered to inner surfaces of the top plate and the bottom cover. Working fluid is contained in the container. All parts of the wick structure have the same thickness. When the bottom cover of the plate-type heat pipe absorbs heat of the heat-generating component, the working fluid is vaporized and transfers heat to the ambient environment at the wick structure mounted on the top plate.

The wick structure intervenes between the vaporized working fluid and the inner surface of the top plate at which the vaporized working fluid can release its latent heat of vaporization and change into condensate. Therefore, the wick structure tends to retard the phase change occurring at the top plate. The heat may transfer to the ambient environment too slowly, and is thus liable to accumulate on the container formed by the top plate and the bottom cover. In due course, the plate-type heat pipe may be overheat, and the heat dissipation efficiency of the plate-type heat pipe is reduced.

What is needed, therefore, is a plate-type heat pipe having good heat dissipation efficiency and stable, reliable performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a plate-type heat pipe in accordance with a first embodiment of the present disclosure, the plate-type heat pipe including a condensing plate, a first wick member, and a second wick member.

FIG. 2 is an isometric, inverted view of the condensing plate of FIG. 1, showing the first wick member mounted on the condensing plate.

FIG. 3 is an enlarged, cross-sectional view of part of the condensing plate with the first wick member, corresponding to line of FIG. 2.

FIG. 4 is similar to FIG. 3, but showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a second embodiment of the present disclosure, with a first wick member and a number of third wick members mounted on the condensing plate.

FIG. 5 is similar to FIG. 3, but showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a third embodiment of the present disclosure, with a first wick member and a number of third wick members mounted on the condensing plate.

FIG. 6 is similar to FIG. 3, but showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a fourth embodiment of the present disclosure, with a first wick member and a number of third wick members mounted on the condensing plate.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a plate-type heat pipe in accordance with a first embodiment of the present disclosure is shown. The plate-type heat pipe comprises a hermetic container 10, a continuous wick structure 30 mounted on an inner surface of the container 10, and working fluid (not shown) contained in the container 10.

The container 10 is made of copper, aluminum, or an alloy thereof, and comprises an elongated condensing plate 11 and a bowl-shaped evaporating plate 13 hermetically contacting the condensing plate 11. The evaporating plate 13 absorbs heat generated by one or more components (not shown) such as electronic devices. The condensing plate 11 dissipates heat transferred from the evaporating plate 13 to the ambient environment.

The evaporating plate 13 comprises an elongated heat absorbing portion 131, two transition portions 133, two extending portions 134, and two sidewalls 135. The transition portions 133 extend outwardly and upwardly from opposite ends of the heat absorbing portion 131, respectively, and are symmetrically opposite each other. The extending portions 134 extend outwardly along opposite horizontal directions from outer ends of the transition portions 133, respectively. The sidewalls 135 extend upwardly from outer ends of the extending portions 134, respectively. In the illustrated embodiment, top ends of the sidewalls 135 are integrally formed with two ends of the condensing plate 11. That is, the evaporating plate 13 and the condensing plate 11 are a single body of the same material without any seams.

The wick structure 30 is made of metallic powder by a sintering process. The wick structure 30 comprises a first wick member 31 and a second wick member 33. The first wick member 31 is adhered to an inner surface of the condensing plate 11. The second wick member 33 is adhered to an inner surface of the evaporating plate 13. Opposite ends of the second wick member 33 connect opposite ends of the first wick member 31, respectively, thereby forming the continuous wick structure 30.

The second wick member 33 comprises an elongated first wick portion 331, two second wick portions 333, two third wick portions 335, and two fourth wick portions 337. The first wick portion 331 is adhered to a top surface of the heat absorbing portion 131 of the evaporating plate 13. The first wick portion 331 is thinner than each of the second wick portions 333. Thus, in general, the working fluid contained in the first wick portion 331 is vaporized faster than the working fluid contained in the second wick portion 333. Accordingly, the heat of the heat absorbing portion 131 is transferred by the first wick portion 331 quickly. The second wick portions 333 extend upwardly and outwardly from opposite ends of the first wick portion 331, respectively, and are symmetrically opposite each other. The second wick portions 333 are adhered to top surfaces of the transition portions 133 of the evaporating plate 13. The third wick portions 335 are horizontal, and extend outwardly from the second wick portions 333, respectively. The third wick portions 335 are adhered to top surfaces of the extending portions 134 of the evaporating plate 13. Each fourth wick portion 337 is adhered to an inner surface of the corresponding sidewall 135 of the evaporating plate 13, and fills a corner formed by the sidewall 135 and the corresponding extending portion 134. A cross-section of each fourth wick portion 337 is substantially triangular. That is, a transverse thickness (horizontal, from left to right, as viewed in FIG. 1) of the fourth wick portion 337 progressively decreases from a bottom end of the fourth wick portion 337 central to a top end of the fourth wick portion 337.

Referring also to FIG. 3, the first wick member 31 is elongated and defines a plurality of through holes 313 therein. In the illustrated embodiment, the through holes 313 are square or rectangular through holes 313, and are arranged in a regular m×n array. The first wick member 31 guides the condensed working fluid back to the opposite ends of the second wick member 33 of the evaporating plate 13. A bottom surface of the first wick member 31 is spaced from a top surface of the first wick portion 331, from top surfaces of the second wick portions 333, and from top surfaces of the third wick portions 335. Because the through holes 313 are defined in the first wick member 31, heat of at least some of the vaporized working fluid is absorbed by the condensing plate 11 directly. Therefore, unlike in other conventional plate-type heat pipes, there is little or even no retardation associated with a wick structure intervening between the vaporized working fluid and the condensing plate 11. Thus, the heat dissipation efficiency of the present plate-type heat pipe is improved. In alternative embodiments, the through holes 313 can be triangular, circular, oval-shaped, elliptical, etc.

Referring to FIG. 4, this shows showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a second embodiment of the present disclosure. A first wick member 31 and a number of third wick members 34 are adhered to an inner surface of a condensing plate 11. In the illustrated embodiment, the third wick members 34 fill top ends of the through holes 313, respectively. Top end surfaces of the third wick members 34 and a top surface of the first wick member 31 are coplanar with one another. Each of the third wick members 34 has a same thickness. A ratio of the thickness of each third wick member 34 to a thickness of the first wick member 31 is in the range from about 1/10 to about ⅘. Because the third wick members 34 are thinner than the first wick member 31, paths of heat transfer of the vaporized working fluid to the condensing plate 11 are generally shorter than those of conventional plate-type heat pipes. Thus, the heat dissipation efficiency of the present plate-type heat pipe is improved. In addition, condensed working fluid contained in the third wick members 34 flows to the first wick member 31 to help drive the working fluid contained in the first wick member 31 to quickly flow back to the opposite ends of the second wick member 33 mounted on the evaporating plate 13. Thus, stable and reliable performance of the plate-type heat pipe can be ensured.

Referring to FIG. 5, this shows showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a third embodiment of the present disclosure. A first wick member 31 and a number of third wick members 35 are adhered to an inner surface of a condensing plate 11. A cross-section of each of the third wick members 35 is a trapezoid. Each third wick member 35 has a smaller end, and a larger end opposite to the smaller end. The smaller ends of the third wick members 35 are all oriented toward the same direction. The larger ends of the third wick members 35 are all thinner than the first wick member 31.

Referring to FIG. 6, this shows showing part of a condensing plate arrangement of a plate-type heat pipe in accordance with a fourth embodiment of the present disclosure. A first wick member 31 and a plurality of third wick members 36 are adhered to an inner surface of a condensing plate 11. A cross-section of each of the third wick members 36 is concave. The cross-section may for example be arcuate or arc-shaped. That is, a thickness of each third wick member 36 gradually increases from a central portion thereof to each of opposite ends thereof. The opposite ends of the third wick members 36 are all thinner than the first wick member 31.

It is to be understood, however, that even though numerous characteristics and advantages of various embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A plate-type heat pipe comprising: a condensing plate; an evaporating plate cooperating with the condensing plate to define a hermetic container, working fluid contained in the container; and a first wick member formed on an inner surface of the condensing plate, the first wick member defining a plurality of through holes therein.
 2. The plate-type heat pipe of claim 1, wherein the first wick member is made of sintered metallic powder.
 3. The plate-type heat pipe of claim 1, wherein a plurality of second wick members fill top ends of the through holes, respectively, and contact the inner surface of the condensing plate.
 4. The plate-type heat pipe of claim 3, wherein each of the second wick members is thinner than the first wick member.
 5. The plate-type heat pipe of claim 4, wherein a cross-section of each of the second wick members is a rectangle.
 6. The plate-type heat pipe of claim 4, wherein a cross-section of each of the second wick members is a trapezoid.
 7. The plate-type heat pipe of claim 6, wherein each of the second wick members has a smaller end, and the smaller ends of the second wick members are all oriented toward the same direction.
 8. The plate-type heat pipe of claim 4, wherein a cross-section of each of the second wick members is concave.
 9. The plate-type heat pipe of claim 8, wherein a thickness of each of the second wick members gradually increases from a central portion thereof to each of opposite ends thereof.
 10. The plate-type heat pipe of claim 1, wherein the evaporating plate comprises a central heat absorbing portion and two sidewalls extending upwardly at opposite sides of the heat absorbing portion and abutting against the condensing plate, a second wick member comprises a first wick portion adhered on an inner surface of the heat absorbing portion and two second wick portions adhered on inner surfaces of the sidewalls.
 11. The plate-type heat pipe of claim 10, wherein the evaporating plate further comprises two transition portions extend outwardly and upwardly from opposite ends of the heat absorbing portion, and the second wick member further comprises two third wick portions adhered on inner surfaces of the transition portions.
 12. The plate-type heat pipe of claim 11, wherein the evaporating plate further comprises two extending portions extending outwardly from opposite ends of the transition portions, respectively, and connecting with the two sidewalls, respectively, and the second wick member further comprises two fourth wick portions adhered on inner surfaces of the extending portions.
 13. The plate-type heat pipe of claim 12, wherein each of the fourth wick portions fills a corner formed by the corresponding sidewall and the corresponding extending portion.
 14. The plate-type heat pipe of claim 10, wherein a cross-section of each of the second wick portions is generally triangular.
 15. The plate-type heat pipe of claim 10, wherein the evaporating plate and the condensing plate are a single body of the same material without any seams.
 16. The plate-type heat pipe of claim 13, wherein a plurality of third wick members fill top ends of the through holes, respectively, and contact the inner surface of the condensing plate.
 17. The plate-type heat pipe of claim 16, wherein each of the third wick members is thinner than the first wick member.
 18. The plate-type heat pipe of claim 17, wherein a cross-section of each of the third wick members is a rectangle.
 19. The plate-type heat pipe of claim 17, wherein a cross-section of each of the third wick members is a trapezoid.
 20. The plate-type heat pipe of claim 19, wherein each of the third wick members has a smaller end, and the smaller ends of the second wick members are all oriented toward the same direction. 